1. Field of the Invention
The present invention relates to a novel process for preparing sialic acid derivatives. More particularly, it relates to the process for preparing 3-O-(sodium(5-acetamide-3,5-dideoxy-alpha-D-glycero-D-galacto-2-noneuro pyranosyl)onate-1,2-di-O-tetradecyl-Sn-glycerol (3).
2. Description of the Related Prior Art
Sialic acid is known to be present as a sialo complex (glycoprotein, glycolipid, oligosaccharide and polysaccharide) on the surfaces of cells of animals and of certain bacteria.
This compound has drawn attention as a singular active molecule that is related to nerve function, cancer, inflammation, immunity, virus infection, differentiation, hormone receptor and the like and is present locally on the surfaces of cells. However, there is no established theory yet as to the role said sialic acid plays in a sialo complex.
It is disclosed in a publication (refer to Laid-Open patent application No. 164798/1984: U.S. Ser. No. 680,498) that various derivatives can be obtained by introducing said sialic acid into a sugar-donor by a known method while introducing a sugar-receptor by a known method, then reacting these two. The method is shown by the following formula: ##STR1##
According to the method, Compound (1) is first dissolved in methanol, to which NaOCH.sub.3 is added and the mixture is agitated at room temperature for one hour. Subsequently the reaction liquor is neutralized by use of cation exchanger (Amberlist A-15) and is then filtered and concentrated under reduced pressure, whereby Compound (2) is obtained as a crystal. (Yield, 67%).
But in the above invention the objective Compound (3) is not disclosed. In other words, the method for preparing Compound (3) directly from Compound (1) is not known. Therefore, said Compound (3) has to be obtained through Compound (2). (Refer to the following formula.) ##STR2##
On the other hand, it is suggested therein that the compound obtained according to the above method is effective as a remedy for nerve troubles.